#!/usr/bin/python
# -*- coding: UTF-8 -*-
#!/usr/bin/env python

import time
import sys

if len(sys.argv) >1:
    INTERFACE = sys.argv[1]
else:
    INTERFACE = 'eth0'

STATS = []
print 'Interface:',INTERFACE

def rx():
    ifstat = open('/proc/net/dev').readlines()
    for interface in ifstat:
        if INTERFACE in interface:
            stat = float(interface.split()[1])
            STATS[0:] = [stat]

def tx():
    ifstat = open('/proc/net/dev').readlines()
    for interface in ifstat:
        if INTERFACE in interface:
            stat = float(interface.split()[9])
            STATS[1:] = [stat]

print 'In    Out'

rx()
tx()

while  True:
    time.sleep(1)
    rxstat_o = list(STATS)
    rx()
    tx()
    RX = float(STATS[0])
    RX_0 = float(rxstat_o[0])
    TX = float(STATS[1])
    TX_0 = float(rxstat_o[1])
    RX_RATE = round((RX - RX_0)/1024/1024,3)
    TX_RATE = round((TX - TX_0)/1024/1024,3)
    print RX_RATE,'MB   ',TX_RATE,'MB'